CA2669072C

CA2669072C - Method for preparing a fire retardant additive for coatings and resulting products

Info

Publication number: CA2669072C
Application number: CA2669072A
Authority: CA
Inventors: Jesus Manuel Martinez Martinez; Julio Cesar Rangel Mata; Ricardo Benavides Perez; Jose Gertrudis Bocanegra Rojas
Original assignee: Servicios Administrativos Penoles SA de CV
Current assignee: Servicios Administrativos Penoles SA de CV
Priority date: 2006-11-10
Filing date: 2007-04-03
Publication date: 2013-01-29
Anticipated expiration: 2027-04-03
Also published as: US9771484B2; JP2013237852A; IL198540A; KR101162183B1; CN101583673B; RU2451044C2; CA2669072A1; JP2010509430A; CN101583673A; IL198540A0; BRPI0716683A2; RU2009122193A; WO2008056966A8; US20120312190A1; KR20090082473A; EP2083053A4; WO2008056966A1; EP2083053A1; MX337770B

Abstract

The invention relates to a method for preparing an additive based on metal hydroxide and, in particular, magnesium hydroxide, to be integrated into coatings in order to provide same with improved fire retardant properties. The average particle sizes of the hydroxide are selected from between 1 nanometre and 10 micrometres, preferably with a very small variation. The magnesium hydroxide is subjected to a washing and dispersion treatment so that it disperses efficiently and does not interfere with the desirable properties of the coating. The materials and conditions used in the treatment and the particle size are selected according to the type of coating. The end coating can be based on water, solvents, oil and alcohol.
Compared to coatings formulated with other fire retardant compounds, smaller weight losses due to burning have been demonstrated with the inventive additive in an ASTM D1360 standard test.

Description

METHOD FOR PREPARING A FIRE RETARDANT ADDITIVE FOR COATINGS AND RESULTING
PRODUCTS
TECHNICAL FIELD FOR THE INVENTION

The present invention is related to the procedures for the preparation of additives for use in coatings applied to structural elements or as finishes for materials susceptible to combustion, such as wood and its derivatives, with the purpose being to provide properties that are flame retarding once the material to be protected is covered; specifically, the invention refers to a procedure for the preparation of an additive formulated with a metallic hydroxide and a mix of a dispersant, a compatible vehicle ( an organize solvent), water and resin that allow the easy incorporation of the additive into the coating.
PRECEDENTS TO THE INVENTION

The need for residential buildings to be constructed or for the realization of other activities:
work, recreation, etc. incorporating means that help control fires and slow the expansion of the fire is well known. For example, some countries have released regulations on materials for the construction of buildings, as much as for the fabrication of the furniture that is contained within them.

The majority of the furniture has coatings that have esthetic purposes as well as for the protection the material which it is made from, nonetheless, the majority of these coatings are inflammable, which when added to the natural combustible property of the base material, generates an excellent source for the spreading of the fire.

Coatings that are flame retarding can be found, they basically are made of phosphates, silicates, borates (intumescent). An intumescent flame retarding material such as those mentioned is characterized because with the action of fire, first, it forms a foam layer that transforms into ash that then forms a crust that impedes the penetration of the fire into the base material.

The metallic hydroxides, on the other hand, are used as flame retarding additives, for example, in polymers, with various different applications: coatings for cables, furniture, roofing tiles "roofing", etc. The magnesium hydroxide has the advantage over other types of flame retarders because it is environmentally friendly and it does not release toxic fumes when utilized as a smoke suppressant.

There already exists a large variety of alternatives to control the problem of fire expansion, through the use of metallic hydroxides. Some examples are mentioned below.

In patent EP 1156092, it describes the fabrication of an adhesive of two components that is created by using magnesium hydroxide, mentioning that said adhesive can be used as a varnish with flame retarding properties.

In the United States patent 6448308, it includes magnesium hydroxide as part of the formulation of a coating that is flame retarding that has a base of red phosphorus. The use of the magnesium hydroxide is specifically used for reducing the production of phosphoric acid during the process of inhibiting the flames.

In United States patent number 4849298, it describes the use of aluminum hydroxide in the creation of paints. It is added directly to the paint and also, it is used as a substitute in some of the conventional types of paint (TiO2, for example). The patent describes the effect of the flame retarding properties of coatings prepared with this additive.

Upon adding the proper amount of previously treated magnesium hydroxide to the traditional coatings for wood, such as varnishes and sealers, or beautifiers, such as paints, water proof coatings, etc. it achieves excellent results as a flame retarder and a smoke suppresser. The coating thus prepared does not change its final appearance (shine, transparency, covering power, mechanical resistance, etc.) Objectives of the Invention.

In light of the problems seen in the previous inventions, one objective of the present invention is to provide an additive that is a flame retarder and a smoke suppresser when used in the preparation of coatings designed to cover and protect surfaces that are susceptible to combustion, and whose efficiency would be better than those offered by the present flame retardant coatings.

Another objective of the present invention is to provide a flame retarding additive that is easily incorporated into the coating before being applied to the surface it is going to protect.

One more objective of the present invention is that the additive incorporates as the flame resistant ingredient a material that does not generate toxic residues when such is the case that it is exposed to flames.

Another objective of the present invention is that the flame retarding ingredient be of the family of metallic hydroxides.

Still another objective of the present invention is that the flame retarding ingredient of the additive of the invention does not form groupings in the interior volume of the coating before its application.

One more objective of the present invention is the flame retarding ingredient of the invention's additive be distributed in a uniform (homogeneous) manner in the film of the final coating on the surface to be covered and protected.

Another objective of the present invention is that the flame retarding additive does not interfere with the fundamental properties of the coating to which it is added, as an example, the transparency of a varnish.

One more objective of the present invention is the flame retarding ingredient of the additive presents grain finesse similar to that of the coating in which it is included.

A SHORT DESCRIPTION OF THE INVENTION

The additive of the coating to the prepared with the procedural ingredient of the invention has as a source of its flame retarding properties a metallic hydroxide, preferably of magnesium, with individual characteristics according to the size of the particle, that is submitted to a treatment associated with the nature of the coating into which it will be incorporated, in a way that the resulting additive is able to be efficiency integrated into the coating selected.

Some characteristics of the additive created with the procedural ingredient of the invention are:
a) An average diameter (D50) of the particle of the metallic hydroxide is selected from a range of from between 1 nanometer to 10 microns, depending on the function of the finish desired of the coating b) The concentration of said particles of metallic hydroxide in the additive can have up to 99% of the weight.

The invention's procedure produces a paste or preferably a suspension of particles of metallic hydroxides treated with other compatible agents (organic solvents or water), dispersants and eventually surfactants, in a substance made up of an organic solvent, a dispersant, a resin and in some cases water, that show the following advantages:

1. To offer better efficiency in the flame retardance of the intumescent additives, that in previous comparative tests of the flame retardance show to obtain better results in the coatings mainly with magnesium hydroxide than those with a base that is composed of phosphates. The results are expressed as a percentage of loss of weight per action of the flame.
2. To be easy to incorporate into the coatings that already exist on the market, without needing to use equipment different from that which is conventionally used for the preparation of coatings, such that the additive has a base that is compatible with the coating into which it will be incorporated.
3. To not alter the final appearance of the coating, which is different from the flame retardants that have a base of phosphorus, in which it is necessary to apply an additional coating that provides the final appearance desired from the finish. With the additive of the invention the characteristics of the shine, the transparency, the ability to cover, the mechanical resistance, etc., of the coating will not be altered.

4. To be environmentally friendly and not harmful to living creatures. In various studies it has been demonstrated that the use of metallic hydroxides in flame retardant coatings have advantages over products such as those that are used as halogenous and phosphoric compounds, and that do not give off toxic gasses, and the release of water in the reaction of the decomposition of the hydroxide helps control the smoke emissions.

5. The surface treatment given to the magnesium hydroxide is selected from a series of surface additives that help make the magnesium hydroxide compatible with the resin of the additive and the coating object, maintaining the characteristics, such as the shine, transparency, covering power, mechanical resistance, etc., of the coating object.

According to an embodiment of the present disclosure, there is provided a procedure for preparing of a flame retarding additive to be incorporated in coatings to protect surfaces susceptible of combustion. The additive has a base composed by a metallic hydroxide as the flame retarding agent and smoke suppresser. The procedure comprises: (a) a first stage of pre-treatment of said flame retarding agent; and (b) a second stage of preparing said additive. The first stage comprises the steps of: providing a humid paste of initial metallic hydroxide; displacing the water which is contained in the metallic hydroxide by means of strong agitation by means of a stirrer into a peripheral velocity from 2m/sec to 30m/sec at least between 5 and 30 minutes, in order to substitute the contained water by an organic solvent, providing a solid phase of said metallic hydroxide; and drying the solid phase of metallic hydroxide to a lower temperature than the boiling temperature of the organic solvent, in order to obtain a dry powder of the metallic hydroxide having an average particle size of 1 nm to 10 microns, and a purity of at least 90%. The second stage comprises the steps of: dispersing the dry powder of the metallic hydroxide by means of a stirrer into a peripheral velocity from 15 m/sec to 30 m/sec; and removing the finished additive from the stirrer. The step of dispersing the dry powder of the metallic hydroxide, a resin and a dispersant are mixed with the same, wherein the resin and dispersant are compatible with the coating in order that the additive is quickly and easily integrated to the coating by means of adjusting the viscosity of the additive to that of the coating.

According to another embodiment there is provided a flame retarding additive to be added into coatings to protect surfaces susceptible of combustion, comprising a metallic hydroxide as a flame retarding agent and a smoke suppresser, an agent, a dispersant and a resin. The metallic hydroxide; agent, dispersant and resin are compatible with the coating in order that the additive is quickly and easily integrated to the coating by means of adjusting the viscosity of the additive to that of the coating. The metallic hydroxide has an average particle size of 1 nm to 10 microns, and a purity of at least 90%; and the metallic hydroxide is in a proportion from 5% to 99% of the weight.

DESCRIPTION OF THE FIGURE

For a better understanding of the description that follows, the attached figure should be regarded when reading the description.

Figure number 1 is a diagram of blocks that represent the procedure for the creation of the additive, the purpose of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The additive prepared according to the procedure of the present invention is created from a metallic hydroxide with an average particle size selected from the range of 1 nanometer to 10 microns, preferably being monodisperse, and having a wide variety of sizes and with a purity of at 5 least 90%.

The metallic hydroxide particles are submitted in a treatment for their integration into the final coating, for that which can be separated from a hydroxide in a diluted suspension, being organic or in dust, without that the compatibility between the initial hydroxide agent and the base of the additive that will formed be limiting to it.

In the preferred form of the present invention, the metallic hydroxide is magnesium hydroxide. It has as an advantage in addition to its flame retarding properties, that it helps control the emission of fumes upon releasing the water when the elements in the reaction break down (1);
Mg(OH)2 --L4 MgO + H2 0 (1) With reference to figure 1, which is a diagram of blocks of the process of the production of the additive of the invention, it is presented in two zones: the first composed of the blocks from (10) to (40) that represent the pretreatment of the particles of metallic hydroxide, and the zone composed of blocks (50) and (60) representing the process of the preparation of the additive itself.

In zone I, or the pretreatment phase, the block (10) represents the flame retarding ingredient that will be used for the preparation of the additive, preferably being a wet paste of metallic hydroxide although for some very specific applications that require the absence of water, it is preferable to use a hydroxide in a dry powdery form. As was mentioned before, the hydroxide is formed by particles with an average size in the range from 1 nanometer to 10 microns and with a purity of at least 90%. This material is added to the following block.

The block (20) represents an operation called the "change of agent" in which the wet paste of the metallic hydroxide is washed with the purpose of displacing the water contained and substituting it for a "compatible" organic solvent, that is, it is incorporated without provoking separation of the stages, with the solvent or the thinner of the final application (the "objective" coating), which will stop in the moment the formation of lumps when it comes in contact with the objective coating; the process takes place with strong agitation, preferably for between 5 and 30 minutes, or for the time deemed necessary. The mix will be maintained in agitation in a turbulent pattern by means of a diffuser with a sharp disk or other device that allows the peripheral velocity to be at least 2 m/sec and up to 30 m/ sec. After the agitation, the separation of the stages results and the process can be repeated until a residual humidity of less than 5% is obtained when in the solid state.

When by the nature of the solvent or the thinner and of the resin of the final application, the metallic hydroxide could react, the need is evaluated, as is indicated by the block (15), in order to give the particles a surface treatment (16) before the operation of the "change of agent" (20), using similar conventional surfactants with the objective coating.

The process of the "change of agent" (20) serves to guarantee that the hydroxide particles do not group together in the diffusion phase (50) in Zone II, in the incorporation to the coating or in the application of the same on to the surface to be treated.

The block of decision (30) indicated that in case that the tolerated residual humidity in the additive is very low, close to zero, due to the nature of the resin and solvents or thinners in the objective coating and once the "change of agent" (20) stage is complete, the solid phase is summated to a process of drying (40), where the temperature of the operation in said drying stage always needs to be lower than the boiling point of the agent. The operation continues until the tolerated residual humidity for the objective coating is obtained.

The result of the operation is a "dry" powder of hydroxide that can be stored for the later preparation of the additive. The product obtained by this means can remain as a "dry" powder dispersible for periods of 12 months.

If in the previous step the humidity content of 5% is reached, the drying stage that is represented by block (30) is omitted.

The product obtained, be it "dry" or wet, coming from one of the two previous steps of the first phase of the process then passes to a process of diffusion (50), in Zone II, which is adequately identified with the preparation of the additive ready for use in the objective coating that is the material of the present invention.

In this stage, the paste or the "dry" powder coming from blocks (20) or (30), are added to a process of diffusion (50) where a resin and a similar dispersant is added to the objective coating, according to the following table:

TABLE 1. Recommended selection of the resin and the dispersant for the preparation of the additive, taking into account the nature of the coating TYPE OF RESIN DISPERSANT RECOMMENDED FOR THE
OBJECTIVE RECOMMENDED DIFFUSION

COATING FOR THE
DIFFUSION
Polyurethane Polyester Copolymer with acidic groups, ethyl ammonium chloride salt of a polycarboxylic acid, ethyl ammonium chloride salt from a non saturated fatty acid, non saturated polyamine amide salt and polyester acids TYPE OF RESIN DISPERSANT RECOMMENDED FOR THE
OBJECTIVE RECOMMENDED DIFFUSION

COATING FOR THE
DIFFUSION

with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight UV Curing Epoxy-acryate Copolymer with acidic groups, ethyl ammonium chloride salt of a polycarboxylic acid, ethyl ammonium chloride salt of a non saturated fatty acid, non saturated polyamine amide salt and polyester acids with low molecular weight, unsaturated salt of polyamine amide and polyester acids with low molecular weight Acrylic- Acrylic- styrene Ammonium salts of an acrylic copolymer, styrene salt of ethyl ammonium chloride and a multifunctional polymer of a anionic character, sodium salt of an acrylic copolymer Vinyl Vinyl Ammonium salt of an acrylic copolymer, salt of ethyl ammonium chloride and a multifunction polymer with an anionic character, sodium salt of an acrylic copolymer Ammonium Ammonium Copolymer with groups of acids, ethyl chloride chloride Resin ammonium chloride of a polycarboxiclic Enamel acids, ethyl ammonium chloride of a non saturated fatty acid, non saturated polyamine amide salt and polyester acids TYPE OF RESIN DISPERSANT RECOMMENDED FOR THE
OBJECTIVE RECOMMENDED DIFFUSION

COATING FOR THE
DIFFUSION

with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight 0% composed Acrylic- styrene. Ammonium salt of an acrylic copolymer, salt of organic Vinyl, Vinilica, of ethyl ammonium chloride a volatiles Acrylic epoxy multifunctional polymer with an anionic character, sodium salt of an acrylic copolymer Nitrocellulosic Ethyl Copolymer with acidic groups, ethyl ammonium ammonium chloride salt of a polycarboxylic chloride or acid, ethyl ammonium chloride salt from a Stabilized non saturated fatty acid, non saturated nitrocellulose polyamine amide salt and polyester acids with low molecular weight, unsaturated polyamine amide salts and polyester acids of low molecular weight Alkaline Alkaline of soy Copolymer with acidic groups, ethyl or coconut, ammonium chloride salt of a polycarboxylic lecithin acid, ethyl ammonium chloride salt from a non saturated fatty acid, non saturated polyamine amide salt and polyester acids with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight Phenolic Phenolic Resin Copolymer with acidic groups, ethyl ammonium chloride salt of a polycarboxylic TYPE OF RESIN DISPERSANT RECOMMENDED FOR THE
OBJECTIVE RECOMMENDED DIFFUSION

COATING FOR THE
DIFFUSION

acid, ethyl ammonium chloride salt from a non saturated fatty acid, non saturated polyamine amide salt and polyester acids with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight The diffusion (50) is done by means of an agitator or a disperser having a peripheral velocity of between 15 and 30 m/sec. The viscosity of the mix is adjusted to that of the objective coating for the addition of the solvent or the thinner that preferably is of the same base that will be used with the coating or at least should be compatible with it. The percentage of dispersant in the mix is maintained between 0.5 and the 10% in relation to the hydroxide in the dry base.

The product (60) obtained from the process of the diffusion (50) is the additive of the invention, the said product that can be in the preferred form, a formulation with up to 99% of its weight in metallic hydroxide.

Among the advantages that the additive has obtained by the process of the invention are that as a consequence of the treatment of the change of agent in stage (20) and the mix with resins and dispersants in stage (50), the product is completely compatible with the objective coating for that which was prepared during the selection of the appropriate surfactant, resin and dispersant according to the table previously included, furthermore, maintaining a high grade of homogeny in the dispersion of the metallic hydroxide particles in the formation. For that which when added to the objective coating, the additive will integrate quickly and easily and it is guaranteed that the particles maintain the homogeny throughout the whole volume and thus, in the layer of the coating after the application onto the surface it is to protect.

In the preferred means of the intention, useful in the case of transparent finishes, particles with an average size in the range of nanoparticles with a low variability (monodisperse) are used with those that the properties of the transparency of the varnish are not altered, that which is not guaranteed with particles of larger sizes or with a non homogenous sample or a sample of wide dispersion.

For that reason, it is suggested that in the preparation of an additive for transparent varnishes to use particles from the extreme low end of the average size range. In the same way, with opaque coatings it is acceptable to use particles of larger sizes, and in the texturized finishes, particles from the extreme high end of the range can be used.

The use of particles from the extreme high end of the range (10 microns) does not guarantee a homogenous distribution in the layer of the coating on the surface that it is to protect, and thus, 5 the flame retardant efficiency is considerably diminished.

Table 2 shows a summary of the selections of the reagants and the parameter values recommended for a variety of classes of conventional coatings used for common applications, with those that is possible to create additives, following the procedure according to the present invention , that will offer the characteristics of being easy to incorporate into the objective 10 coating, homogenous (uniform) distribution of the particles of the flame retarding and smoke repressing ingredient, and conservation of the desired properties of the coating to name a few.
Table 2. Materials and parameters recommended for various types of coatings.

Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)2 initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion Varnishes N 1 to 190 Less than Aryl Less than Copolymer Ketenes, Less nm 65% Ketenes, aryl 5% with acidic esters, than alcohols, alcohols, 60 groups, ethyl t Glycol ester, ammonium glycol m r glycol ether, chloride salt esters, etc. glycol o of a esters, polycarboxyli etc.
c c acid, ethyl e ammonium II chloride salt from a non u saturated fatty acid, non saturated s polyamine e amide salt and polyester acids with low molecular weight, unsaturated polyamine amide and Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)2 initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion polyester acids of low molecular weight E 1 to 190 Less than Aryl Less than Copolymer Hydro Less t nm 65% Ketenes, aryl 5% with acidic carbonate than h alcohols, groups, ethyl , ketenes, 20 y glycol ester, ammonium esters, m glycol ether, chloride salt alcohols, a etc. of a glycol m polycarboxyli ethers, glycol m c acid, ethyl esters o ammonium n chloride salt from a non u saturated m fatty acid, non saturated c polyamine h amide salt and o polyester r acids with low d molecular e weight, unsaturated polyamine amide and polyester acids of low molecular weight P 1 to 190 Less than Aryl Less than Copolymer Hydro Less nm 65% Ketenes, aryl 5% with acidic carbonate than h alcohols, groups, ethyl , ketenes, 20 Glycol ester, ammonium esters, prn e glycol ether, alcohols, etc. chloride salt glycol n ofa ethers, polycarboxyli glycol Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)2 initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion 0 c acid, ethyl esters ammonium chloride salt from a non saturated c fatty acid, non saturated polyamine amide salt and polyester acids with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight P 1 to 190 less than Aryl less than Copolymer Hydro less nm 65% Ketenes, aryl 5% with acidic carbonate than o alcohols, groups, ethyl , ketenes, 20 Glycol ester, ammonium esters, m glycol ether, chloride etc. e salt glycol of a y polycarboxyli g~yco~' u c acid, ethyl esters ammonium r chloride salt e from a non saturated t fatty acid, non h saturated polyamine a amide salt and n polyester Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)Z initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion e acids with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight P V 1 to 5 pm less than Water less than Ammonium Water less 5% 5% salt of an than A i 50 acrylic n copolymer, m salt of ethyl N y ammonium chloride a T I
multifunctio S nal polymer with an anionic character, sodium salt of an acrylic copolymer A 1 to 5 dim less than Water less than Ammonium Water less C 5% 5% salt of an than r acrylic 50 Y copolymer, m salt of ethyl ammonium c chloride a V multifunctio i nal polymer n with an y anionic character, sodium salt of an acrylic copolymer Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)2 initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion 0 1 to 2 m less than Aryl less than Copolymer Hydro less 5% Ketenes, aryl 5% with acidic carbonate than alcohols, groups, ethyl , ketenes, 50 Glycol ester, ammonium esters, m glycol ether, chloride etc. e salt of a glycol ethers, polycarboxyli glycol c acid, ethyl esters ammonium chloride salt from a non saturated fatty acid, non saturated polyamine amide salt and polyester acids with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight E 1 to 190 less than Aryl less than Ammonium Water less nm 5% Ketenes, aryl 5% salt of an than m alcohols, acrylic 20 U Glycol ester, copolymer, m glycol ether, salt of ethyl etc.. ammonium chloride a s multifunctio nal polymer with an o anionic character, Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)2 initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion n sodium salt of an acrylic copolymer U 1 to 190 less than Aryl less than Copolymer Alcohols less V nm 2% Ketenes, aryl 2% with acidic with 6 than alcohols, groups, ethyl carbons 15 Glycol ester, ammonium or more, m glycol ether, chloride salt esters etc. of a with 6 carbons polycarboxyli or more, c acid, ethyl monomer ammonium s chloride salt from a non saturated fatty acid, non saturated polyamine amide salt and polyester acids with low molecular weight, unsaturated polyamine amide and polyester acids of low molecular weight T S 1 to 5 m less than Water less than Ammonium Water less t 5% 5% salt of an than E y Acrylic- acrylic 60 X r styrene copolymer, m e salt of ethyl T
e ammonium chloride a a multifunctio Type of Size of Humidity Agent for Humidity Dispersant for Solvent or Fines coating the in the the process of the the diffusion thinner se Mg(OH)2 initial of the Hydroxid for the Particles hydroxid "change of e before diffusion e Agent" the diffusion U r nal polymer Y with an R
anionic character, I c sodium salt Z of an acrylic E copolymer A 1 to 5 pm less than water less than Ammonium water less D C 5% 5%
salt of an than r acrylic 60 Y copolymer, m i salt of ethyl ammonium c chloride a v multifunctio nal polymer n with an Y anionic character, sodium salt of an acrylic copolymer For a better understanding of the use of the data contained in tables 1 and 2, the following examples are realized according to standards ASTM D1360. They offer illustrations of diverse alternatives for the creation of the additives according to the procedure of the present invention.
Example 1. Preparation of the additive to be used in a coating with an ethyl ammonium chloride base having a residual humidity of less than 5%.

1. Separate nanometric magnesium hydroxide with a humidity of 65% that has the following distribution of particle sizes: D1Q, 59.0 nm; D50, 92.7 nm; D90, 153 nm;
measured by laser ray diffraction in a machine marked COULTER LS 230. For the purpose of illustration, we will use 1200 grams.
2. Place the magnesium hydroxide in a 6 Liter recipient that has a pour spout.

3. Pour 3600 grams of ethylene glycol butyl ether, and agitate (dispersing) with a dispersing propeller to a peripheral velocity of between 5 and 30 m/ sec. This agitation (dispersion) is maintained for a period of between 5 and 15 minutes.
4. With the help of a centrifuge, a decanter, a filter, or other means of separating solids from liquids, as much of the liquid part as possible is removed, depending on the function of the equipment selected for completing the separation.
5. With the paste obtained, repeat steps 3 and 4 until the content of the water in said material is less than 5%.
6. The paste then from step 5 is placed in an appropriate drying machine and the organic solvent is eliminated. The dryer should not be operated at a temperature higher than the boiling point of the solvent, this guarantees that the power of magnesium hydroxide obtained does not suffer changes in the side of the particle and that its integration to the flame retarding additive will be efficient.
7. Place 590 grams of ethyl ammonium chloride into a 1.0 liter Berzelius beaker without a spout.
8. The beaker will be placed in a diffusion machine provided with a deflector and a propellant for the diffusion.
9. The resin is to be agitated at a moderate velocity: peripheral velocity of between 1 and 5 m/s.
10. Pour in ten grams of the dispersant DCM-305 (a copolymer with groups of acids), that is compatible with the resin.
11. Add to it 400 grams of the magnesium hydroxide that was obtained in point 6.
12. Maintain medium agitation until the magnesium hydroxide is completely humid.
13. Once the mix is homogenous, the velocity of the disperser is increased until it has enough cutting force that guarantees an efficient distribution: peripheral velocity between 15 and m/s.
14. The diffusion is maintained during 15 minutes or the time necessary to reach the finesse of the application.

Example 2. Preparation of the additive to be used in a coating with a nitrocellulosic base that has 30 a required residual humidity of less than 5%.

1. Place 490 grams of the nitrocellulose resin in a 1.0 liter Berzelius beaker without a spout.
2. Place the beaker in a diffusion machine provided with a deflector and a propellant from the diffusion of 7 centimeters of diameter.
3. Agitate the resin at a moderate velocity.
4. Pour 10 grams of the dispersant DCM-305 (a copolymer with groups of acids), that is compatible with the resin.
5. Add in 400 grams of dry magnesium hydroxide with particle size being an average of 100 nanometers.
6. Maintain medium agitation until the magnesium hydroxide is completely humid.

7. Once the mix is homogenous, the velocity of the disperser is increased until it has enough cutting force that guarantees an efficient distribution: peripheral velocity between 15 and 30 m/s.
8. The diffusion is maintained during 15 minutes or the time necessary to reach the finesse of the application.

The flame retarding additive for the ethyl ammonium chloride varnish, prepared in Example 1, can be mixed in different proportions with any ethyl ammonium chloride varnish that is found on the market. Also, the flame retarding additive for the nitrocellulose based sealer prepared in Example 2 can be mixed with any nitrocellulose based sealer that is on the market.

The most frequent is that in the varnish of an item made of wood it be used as much as a sealer as a varnish. Table 3 shows different combinations of sealers and varnishes mixed with the flame retarding additives prepared in Examples 1 and 2, and the results to summit them to the flame test according to the ASTM D1360.

Table 3. Effect as the percentage of weight lost by the action of the flames, of the content of Mg(OH)2 in a nitrocellulose based sealer and a varnish with an ethyl ammonium chloride based resin both applied to a sample of wood.

Test Number 1 2 3 4 Control Intumes Group cent Sealer Type of Nitro- Nitro- Nitro- Nitro- Nitro-resin cellulose cellulose cellulose cellulose cellulose Additive / Sealer 1/ 7 1/ 7 1/ 1 1/ 1 0 -Varnish Type of resin Ethyl Ethyl Ethyl Ethyl Ethyl ammonium ammonium ammonium ammonium ammonium -chloride chloride chloride chloride chloride Additive Varnish Loss of weight ($) 7.8 5.5 3.5 1.7 62.8 17.5 Table 4 shows the rest of the examples of the additives prepared with different types of resins that have applications to different types of coatings.

Table 4. Preparation of a flame retardant additive Ex. Metallic D50 Inicial Change Final Resin of the Dispersant Surfacta # Hydroxid mm Humid of Humidi coating nt e ity Vehicle ty ethylene Ethyl glycol >5% Copolymer with 1 Mg(OH)2 0.0927 65% butyl >5% ammonium acid groups ether chloride 2 Mg(OH)2 0.0927 <5% <5% Nitrocellulos Copolymer with e acid groups Methyl Copolymer with hydroge 3 Mg(OH)2 0.0927 <5% - <5% Phenolic n acid groups polysilo xane Methyl <5% <5% Polyurethan Copolymer with hydroge 4 Mg(OH)2 1.102 <5% - <5% e acid groups n polysilo xane Ammonium salt Methyl made of an hydroge Mg(OH)2 1.102 55% water >5% Vinyl acrylic n polysilo copolymer xane Ammonium salt Methyl made of an hydroge 6 Mg(OH)2 1.102 55% water >5% Acrylic vinyl n acrylic copolymer polysilo xane Methyl Ethyl Copolymer with hydroge 7 Mg(OH)2 1.102 <5% - <5% ammonium n chloride acid groups polysilo xane Ex. Metallic D50 Inicial Change Final Resin of the Dispersant Surfacta # Hydroxid mm Humid of Humidi coating nt e ity Vehicle ty Ethyl Ammonium salt Methyl ammonium made of an hydroge 8 Mg(OH)2 1.102 55% water >5% n chloride acrylic 0-VOC copolymer polysilo xane Table 4. Preparation of a flame retardant additive (continued) Ex. Metallic D50 Inicial Change Final Resin of Dispersant Surfacta # Hydroxide mm Humid of Humidi the coating nt ity Vehicle ty Copolymer with acid groups Acrylic Methyl non saturated hydroge epoxy 9 Mg(OH)2 1.102 <5% - <5% catalyzed polyamine n by UV amide salt and polysilo polyester acids xane with low molecular weight Ammonium salt Methyl Acrylic - made of an hydroge 10 Mg(OH)2 1.102 55% water >5% n styrene acrylic copolymer polysilo xane Methyl Ethyl Copolymer with hydroge 11 AI(OH)3 6.86 >5% - <5% ammonium n chloride acid groups polysilo xane Ammonium salt Methyl made of an hydroge 12 AI(OH)3 6.86 40% water >5% Vinyl n acrylic copolymer polysilo xane Ex. Metallic Dso Inicial Change Final Resin of Dispersant Surfacta # Hydroxide mm Humid of Humidi the coating nt ity Vehicle ty Methyl Polyuretha Copolymer with hydroge 13 AI(OH)3 6.86 <5% - <5% ne acid groups n polysilo xane Ethyl Ammonium salt Methyl ammonium made of an hydroge 14 AI(OH)3 6.86 40% water >5% n chloride acrylic 0-VOC copolymer polysilo xane The effects of the use of the additive with magnesium hydroxide in the wood coatings in the previous tests are illustrated in Table 5. They show the result of the examples of the application of the prepared additive according to the previously described procedure.

The effect of the flame retardant when the coating includes magnesium hydroxide can be clearly observed. In the physical tests, it can be seen that that there is no change in the final appearance of the coating with the additive of the invention after its application with respect to the appearance that the coating offers without the additive; this is also valid for coatings that have a high transparency such as varnishes.

Table 5. Effect of the flame retarding additive, as a percentage of the weight loss, applied in a sample of wood according to the ASTM D1360.

Sealer Coating Metallic Weight Loss Hydroxide (%) Type of Additive / Type of Coating Additive /
Sealer Sealer Coating Nitrocellulose 1/7 Ethyl ammonium 1/7 Mg(OH)2 7.8 chloride varnish Nitrocellulose 1/7 Phenolic Varnish 1/7 Mg(OH)2 3.6 Nitrocellulose 1/1 Ethyl ammonium 1/1 AI(OH)3 14.3 chloride varnish - Intumescent - - 17.5 Nitrocellulose - Ethyl ammonium - - 62.8 chloride varnish Nitrocellulose - Phenolic Varnish - - 66.1 Ethyl ammonium 1/1 Mg(OH)2 6.7 chloride varnish Varnish of Acrylic 1/1 Mg(OH)2 30.1 epoxy catalyzed by UV
Polyurethane 1/1 Mg(OH)2 11.4 varnish Ethyl ammonium - - 61.3 chloride varnish Varnish of Acrylic - - 71.0 epoxy catalyzed by UV
Table 5. Effect of the flame retarding additive, as a percentage of the weight loss, applied in a sample of wood according to the ASTM D1360 standard. (continued) Sealer Coating Metallic Weight Loss Hydroxide (%) Type of Additive / Type of Coating Additive /
Sealer Sealer Coating Polyurethane - - 72.4 varnish Ethyl ammonium 1/1 Mg(OH)2 2.8 chloride enamel - Ethyl ammonium - - 8.2 chloride enamel - Acrylic Styrene 1/1 Mg(OH)2 10.7 water- proofer - Acrylic Styrene - - 58.4 water -proofer - Acrylic Vinyl Paint 1/1 Mg(OH)2 5.2 - Vinyl Paint 1/1 Mg(OH)2 6.0 Acrylic Vinyl Paint - - 52.6 Vinyl Paint - - 52.6 In this aspect, the size of the hydroxide particles is important, as well as the uniformity of the size and the homogeny of the distribution of the particles in the final layer of the coating once applied.

As has been described and illustrated through the previous examples, the present invention is directed to the preparation of an additive that has the properties of a flame retardant and a suppresser of smoke, without affecting the properties of the coating to which it is added.

In the examples, there has been used some common coatings for the protection of surfaces, in particular wood and its derivative, as can be seen by a technician with knowledge of the art, these examples do not limit the reach of the invention but they are to be illustrative of the same , and the use of the additive in other coatings for the application to other surfaces, is found to be also within the reach of the present invention that, thus should be considered in light of the following claims.

Claims

1. A procedure for preparing of a flame retarding additive to be incorporated in coatings to protect surfaces susceptible of combustion; the additive having a base composed by a metallic hydroxide as the flame retarding agent and smoke suppresser, said procedure comprises: (a) a first stage of pre-treatment of said flame retarding agent;
and (b) a second stage of preparing said additive; wherein:

the first stage comprises the steps of;

providing a humid paste of initial metallic hydroxide;

displacing the water which is contained in the metallic hydroxide by means of strong agitation by means of a stirrer into a peripheral velocity from 2 m/sec to 30 m/sec at least between 5 and 30 minutes, in order to substitute said contained water by an organic solvent, providing a solid phase of said metallic hydroxide;

drying said solid phase of metallic hydroxide to a lower temperature than the boiling temperature of said organic solvent, in order to obtain a dry powder of the metallic hydroxide having an average particle size of 1 nm to 10 microns, and a purity of at least 90%;
wherein the second stage comprises the steps of:

dispersing said dry powder of the metallic hydroxide by means of a stirrer into a peripheral velocity from 15 m/sec to 30 m/sec;

removing the finished additive from the stirrer;
and wherein in the step of dispersing the dry powder of the metallic hydroxide, a resin and a dispersant are mixed with the same, wherein said resin and dispersant are compatible with said coating in order that said additive is quickly and easily integrated to said coating by means of adjusting the viscosity of said additive to that of the coating.

2. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the initial metallic hydroxide is in a suspension form.

3. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the initial metallic hydroxide is in a substantially dry solid form.

4. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the water displacing is repeated until a residual humidity of 5% in the solid stage is obtained.

5. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the organic solvent for the water displacing is selected from the group of solvents or thinners used in coatings comprising a solvent or thinner, in a such way that it is compatible with the solvent or thinner of the coating.

6. The procedure for the preparation of a flame retarding additive according to claim 5, wherein the agent for the displacing of the water is the same to the solvent or thinner of the coating.

7. The procedure for the preparation of a flame retarding additive according to claim 1, wherein whether the metallic hydroxide reacts with the selected agent for the water displacing or with the resin of the coating, the metallic hydroxide is submitted to a superficial treatment with surfactants before the displacing of the water.

8. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the step of drying is maintained until the tolerated residual humidity by the coating is obtained.

9. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the metallic hydroxide obtained in the first stage of the pre-treatment contains a humidity from between 0% and 5% which is necessary for the compatibility between the resin and the coating.

10. The procedure for the preparation of a flame retarding additive according to claim 9, wherein said metallic hydroxide is capable of being stored for large periods of time, until the preparation of the dispersion which forms the flame retarding additive is required.

11. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the metallic hydroxide dispersible provided to the second stage has a humidity content from between 0% and 5%, which is the maximum percentage tolerated by the coating.

12. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the percentage of dispersant in the mix is maintained between 0.5% and 10% in accordance to the metallic hydroxide in a dry base.

13. The procedure for the preparation of a flame retarding additive according to claim 1, wherein the product obtained is a flame retarding additive that contains from 5% to 99% of the weight of metallic hydroxide.

14. A flame retarding additive to be added into coatings to protect surfaces susceptible of combustion, comprising a metallic hydroxide as a flame retarding agent and a smoke suppresser, an agent, a dispersant and a resin, wherein:

said metallic hydroxide; agent, dispersant and resin are compatible with the coating in order that said additive is quickly and easily integrated to said coating by means of adjusting the viscosity of said additive to that of the coating;

wherein: a) the metallic hydroxide has an average particle size of 1 nm to 10 microns, and a purity of at least 90%; and b) the metallic hydroxide is in a proportion from 5% to 99% of the weight.

15. The flame retarding additive according to claim 14, wherein the dispersant is present in a quantity from between 0.5% and 10% in basis to the hydroxide in its dry form.

16. The flame retarding additive according to claim 14, wherein the additive has a humidity content equal to or less than that tolerated by the coating.

17. The flame retarding additive according to claim 14, wherein the metallic hydroxide is magnesium hydroxide.

18. The flame retarding additive according to claim 14, wherein said additive presents a grain finesse similar to that of the coating.

19. The flame retarding additive according to claim 14, wherein the size of the magnesium hydroxide particles are in the lower end of the coatings range which require transparent finish.

20. The flame retarding additive according to claim 14, wherein the size of the magnesium hydroxide particles are in the upper end of the coatings range which has an opaque or texturized finish.